Can Obesity Increase the Risk of Breast Cancer?

Although smoking cigarettes and drinking alcohol increase the risks of developing cancer, being overweight increases the risks of developing breast cancer, particularly in women who are beyond menopause. New research shows a correlation between breast cancer in postmenopausal women and high sex hormone levels such as testosterone and estrogen.

According to the study at the University of Oxford, commissioned by Cancer Research UK, obesity is becoming the biggest driving force behind the most common form of breast cancer, beating out cigarettes and alcohol as a leading cause of death for women beyond menopausal age.

According to the researchers who conducted the study, “Although the breast cancer risk for postmenopausal women is known to be associated with levels of sex hormones such as estrogens, the factors that determine the levels of these hormones are not well understood. While obesity is thought to increase the risk of cancer through its association with high levels of estrogen, it is unclear how other risk factors affect sex hormone levels.” The researchers preformed an analysis that combined the results of thirteen previously completed studies of 6,000 women who did not have breast cancer to see how their hormone levels were related to age, alcohol and cigarette use, and weight.

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The BBC study, which was published in the British Journal of Cancer, concluded that “Compared to slim women, the hormone levels, chiefly the estrogen hormones, were higher in overweight women.” The study also found that women who drink two or more alcoholic drinks a day, or who smoked 15 or more cigarettes a day, had higher hormone levels. Although the findings give weight to the importance of maintaining a healthy weight, it should be noted that because the factors were analyzed at only a single point in time, the study does not take into account how factors such as lifestyle changes and health issues are related to each other.

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For example, the study cannot prove whether or not the rise in a woman’s hormone levels causes weight gain, or if a woman’s weight gain causes a rise in hormone levels. The study did not analyze data on women with cancer, instead it focused on whether obesity and lifestyles were related to hormone levels which can increase cancer risk.